Building blocks have developed over time. Originally, solid bricks were used. These evolved into cinder blocks. These blocks are formed of concrete and have pair of holes formed through the blocks. These holes make the blocks considerably lighter, and can be used as a better handle to help carry and position the blocks, and a space within the block to hold reinforcing bar and to be filled with concrete once the blocks are placed. The basic cinder block has changed little over time. However, new blocks have been developed to make construction more flexible. For example, blocks today are curved, they have different structural configurations, and are even made of light weight plastic foam.
A number of blocks were developed to better insulate block walls. A normal cinder block th at is filled with cement has no space for insulating material. Although the blocks do provide some insulating properties, such blocks are best known as heat absorbers. Thus, a block wall absorbs heat in the summer and holds that heat, which causes an increased cooling load. Similarly, in winter, they absorb cold, increasing the heating load. To solve this problem, several blocks have been developed to allow for insulative material to be placed within the blocks, thereby breaking the thermal flow paths. Examples of these blocks are found in the following U.S. Patents. U.S. Pat. No. 3,593,480 teaches a block that has an outer appearance that is similar to an ordinary cinder block. The block is actually a plastic shell that has cavities that are filled with concrete. The block also has open areas that can be either dead air space or can be filled with insulating material. The problem with these blocks is that they must be filled with concrete, and the concrete must be cured, before they can be set into place. Once filled, these blocks become heavy and are difficult to work with. U.S. Pat. No. 4,380,887 to Lee teaches a cinder block that is made with special slots that allow foam insulation panels to be inserted into the slots. The idea is to break up the thermal conductivity through the block webs. Although this design is an improvement, it still requires a full size block, with all the weight problems associated with that weight. Moreover, the insulating panels are designed to be inserted from both the top and the bottom of the block. This slows down the construction process, if the blocks are insulated in the field. It adds to the cost of installation if the insulation is added at the factory. U.S. Pat. No. 4,498,266 to Perreton teaches a cinder block that has a center channel to hold blocks of insulation. U.S. Pat. No. 4,745,720 to Taylor teaches a cinder block that is cut in two lengthwise. The split block is then reassembled with a special insulating channel in the center. Special clips are provided to secure the insulation within the block. U.S. Pat. Nos. 5,209,037 and 5,321,926 teach cinder blocks that have complex curves formed in them to receive insulation. Although these blocks provide improved insulating capabilities, the complex curve design increases cost and provides minimal hand holds for block placement. This makes construction more difficult and slow, which also drives up cost.
Finally, U.S. Pat. No. 4,841,707 to Nova teaches an alternative direction in block wall construction. As noted above, the problem with ordinary blocks is the transmission of cold and heat through the blocks themselves. The blocks above seek to break the transmission path. Another way to do this is to use a double wall. Such a wall has the outward appearance of an ordinary block wall, but has an outer block wall and an inner block wall that are connected by bracing. The space between the walls can be filled with insulating material to provide the best possible levels of insulation.
The problem with the Nova wall is that there are no blocks. Both walls are poured. Although this is an acceptable building method, it can be expensive, especially for residential type construction.